Effect of curing temperature on the mechanical properties of hydrogen silsesquioxane thin films

The mechanical properties and thermal stresses of hydrogen silsesquioxane ( HSQ) thin films cured at different temperatures have been investigated by a nanoindentor and a profilometer. In this study, the correlations between s tructure change, Si-H/Si-O ratio, modulus, hardness, and calculated CTE of HSQ films have been established. The results show that the Si-H/Si-O ratio of HSQ films decreases with increasing curing temperature due to the loss o f Si-H bonds when it forms the network structure at higher curing temperatu res. In addition, both the modulus and hardness of HSQ films increase with increasing curing temperature. However, the calculated coefficient of therm al expansion (CTE) decreases with increasing curing temperature. These resu lts indicate that the increase in modulus and hardness and the decrease in CTE are due to the conversion of Si-H into Si-O bonds with the reduction in porosity when forming the network structure in the HSQ films at higher cur e temperatures. (C) 1998 Elsevier Science S.A. All rights reserved.